With respect to a surface-emitting type of optical devices, in particular, LED (Light Emitting Diode), recently, the characteristics thereof have been improved, and expectations for usage expansion are high. According to the related art, an LED is mounted in a plastic case and a micro lens or the like is disposed in a light path to focus light. Alternatively, all of an LED and a substrate having the LED mounted thereon are molded in a transparent resin and the surface of the resin is shaped into a smooth sphere or the like such that the resin is used as a lens to focus light. Such light-emitting parts having LEDs have been used for electric bulletin boards, large-sized screens for films, lights of signaling apparatuses, illuminations, etc.
However, since LEDs consume a smaller amount of power and have a longer light-emitting lifetime as compared to conventional electric bulbs, their use has been taken into consideration for being applied to a wide range of illumination fields including electric lamps, interior illuminations, illuminations for automobiles, backlights for liquid crystal screens, etc.
Further, a technique relating to such a kind of submount is disclosed in Patent Publication 1, for example.
Patent Publication 1: Japanese Laid-Open (Unexamined Patent Application Publication) No. 2005-183558
In consideration of the above application for illumination fields, it is required to put a number of LEDs together on a plane, to make the LED emit light, and to focus the light. The reason comes from the fact that the intensity of light of one LED element is considerably weaker as compared to an electric bulb. Further, in the case of LED elements molded by use of a resin or the like according to the related art, there is a limitation in densely arranging LED elements.
Further, as an output of an LED element becomes brighter, the temperature of the LED element easily increases, while the luminous efficiency thereof easily decreases. Therefore, in order to apply LED elements to various fields including lights, illuminations, etc., it is required to densely arrange high-power LED elements and to effectively focus light.
In order to focus light, in general, lenses are used. However, if lenses are used for every LED element, the cost results in a rise in product price and supporting members are needed to fix the lenses over the LED elements.
Moreover, in order to manufacture inexpensive submounts for mounting optical devices, production rationalization such as manufacturing a lot of products with a wafer-shaped substrate in batch while reducing the materiel expense and processing cost is necessary.